Radiograph marking apparatus



Aug. 18, 1953 e. LOTT 2,649,547

RADIOGRAPH MARKING APPARATUS Filed Aug. 11, 1949 mvsmmz Y GORDON L. LOTTB mum,

ATTORNEYS Patented Aug. 18, 1953 RADIOGRAPH MARKING APPARATUS Gordon L.Lott, Vancouver, British Columbia, Canada Application August 11, 1949,Serial No. 109,695

6 Claims. 1

This invention relates to improved apparatus for marking radiographs.

In making radiographs, a radiograph film or plate is placed in acassette between the adjacent contact faces of two fluorescent screens.When X-rays are directed on to the screens, the latter convert saidX-rays into actinic rays. Some of the X-rays are converted at the firstscreen while others are transmitted therethrough and converted at thesecond screen. Both the X-rays and the actinic rays produce a,shadowgraph of varying degrees of any object placed between the sourceof the X-rays and the film or plate.

It is well-known that at the present time markings and identificationson X-ray films are blackened out almost beyond recognition when highvoltages are used for making radiographs of thick parts of the humananatomy. It has been discovered that it is not the high voltage which isresponsible for obliterating the markings, but an excess amount ofactinic rays produced by the fluorescent screens.

An object of the present invention is the provision of apparatus inwhich radiographs may be clearly marked without danger of the markingsbeing obliterated when high voltages and dosage are used.

Another object is the provision of apparatus in which a radiograph maybe clearly marked Without affecting the contact between the film and thefluorescent screens.

Another object is the provision of radiograph apparatus in which an areakept free of actinic rays in order that identifying indicia locatedoutside the cassette may be reproduced on the film without danger ofobliteration.

Yet another object is the provision of radiograph apparatus including anarea therein free of a-ctinic rays and having identifying indiciaoutside the apparatus in which it is impossible for said area andindicia to get out of line with each other, or for either of these tcinterfere with the Shadowgraph of the object being radiographed.

Examples of the radiograph marking apparatus are illustrated in theaccompanying drawings, in whic Figure l is an elevation of an opencassette,

Figure 2 is an elevation of a closed cassette showing the surfacethereof which faces the source of the X-rays,

Figure 3 is a fragmentary section taken on the line 3-3 of Figure 2,

Figure 4 is an end view of a fluorescent screen incorporating one formof the invention, and,

Figure 5 is a perspective view of a screen showing another form of theinvention.

Referring to Figures 1 and 2, H] is a cassette of well-knownconstruction. This cassette consists of a metallic frame ll having awall I2 formed of suitable material, such as Bakelite, secured to oneface thereof, and a metallic cover l3 hingedly mounted on its oppositeface. Suitable means is provided for locking the cover in closedposition. This may be in the form of a bar [5 hingedly mounted at 16 tothe outer surface of the cover and adapted to extend beyond oppositesides thereof, as clearly shown in Figure 1. When the cover is closed,this bar is swung into a position with its opposite ends beneath lugs llmounted on opposite sides of the frame to hold the cover in closedposition.

Two fluorescent screens 20 are located within the cassette, one againstthe inner surface of the wall I? and one against the inner surface ofthe cover l3. These screens are secured in place in any convenientmanner so that they are separated when the cover 13 is opened. When thecover is closed, the adjacent surfaces of the screens come together andare adapted to contact a radiograph film or plate 22 which has beeninserted in the cassette. The apparatus described so far is well-knownand is in common use today.

Each of the fluorescent screens 20 is formed with a defluorized area 25,the area of one screen being in line with the corresponding area of theother screen when the cover I3 of the cassette is closed. It isdesirable that the area of each screen be located at a corner thereofand extend into the screen some distance from each of the two sides atsaid corner.

The defiuorized area may be formed by cutting away a portion of thescreen at the desired point. This area may be left vacant, but it ispreferably filled with or covered by a block of material which isimpervious to actinic rays.

Fluorescent screens used in these cassettes are usually provided with abacking 21 formed of a cardboard composition, see Figure 4. Thesebackings are located on the surface of the screen which is remote fromthe radiograph film when the cassette is closed.

In formin the efi z area 5, the r st s in the screen in this area may beremoved to form a recess extending part way through the screen, orcompletely through the screen, as illustrated in Figure 4. This recessis filled with a block 29 of any suitable material which is imperviousto actinic rays and which will permit X-rays to pass therethrough. Thisblock may be formed of a composition consisting of wood fibre andplastic material,.,dyed Jolack,;or. may be any other-suit- 3 able blackmaterial, such as paint or paper. It is highly desirable that the blOckbe built up so that its outer surface is flush with the surface 3| ofthe screen which comes into contact with the film. This eliminates thepossibility of defective screen and film contact.

The wall I2 of the cassette may be marked as at 35 to indicate theboundary of the fluorescent screens. It may also be marked as at 36 toindicate the position of the defiuorized areas of the screens. Suitableidentifying indicia 31., such as numbers and/or letters, are placed onthe outside of the cassette within the area bounded by the lines 35 and36, where they are located over the defiuorized areas or imperviousblocks .of the screens. These indicia are formed of any suitablematerial, such as lead, which is opaque to X-rays. The indicia may beretained in position in any convenient manner, such" as by means of aframe 38.

In operation, a radiograph film is placed in the cassette and the coverl3 thereof closed, so that said film is between and in contact with theinner surfaces of the .fiuorescent screens 20. The desired identifyingindicia 3.! are placed on the outside of the cassette in the areabounded by the lines 35 and 136. This means that the indicia are in linewith the aligned impervious blocks 29 of the screens. 'When X-rays aredirected through the object to be radiographed to the cassette, such asa part of the human body, the denser parts thereof will form ashadowgraph on the film. At the same time, the indicia will be clearlymarked on the film because the X-rays cannot pass through them. Theindicia cannot be burned out since the impervious blocks 29 prevent theactinlc rays from entering the defiuorized area. Thus, no matter howhigh the voltage or dosage used or the amount of secondary raysinvolved, the indicia will be quite clear. There is no danger ofdefluorized areas moving from their proper positions in line with theindicia, and there is absolutely no danger of either the indicia orfiefluorized areas interfering with the shadowgraph as said indicia andareas are fixed relative to the radiograph film.

The defluorized area in each screen may be formed by securing a verythin layer of black material, such as paper, to the surface of thescreen at the desired point, or by covering said area with black paint.This makes the .covered portion of thescreenin'active as far as theactinic rays are concerned. If the covering is kept thin enough, it willnot materially interfere with the contact between the screen surfacesand the film.

Figure '5 illustrates a fluorescent screen 20 having an impervious block29, as described above. However, a barrier 38 surrounds the block and isflush with the .contact surface of the screen. This barrier is formed ofa material, such as lead, which is impervious to both actinic andX-rays. The barrier prevents any rays which :may be travellingsubstantially horizontally from reaching the defluorized areas. Ifdesired, the barrier may be used without the block.

Some results have been obtained by forming a defiuorized area in theback screen only, that is, in the screen which is farthest from thesource of X-rays. While the impervious blocks in both screens may beformed of material impervious to actinic rays, but which will permit thepassage of X-rays, it is to be understood that the block in :the backscreen may be impervious to 4 both rays. In this case, it may be formedof a material such as lead.

What I claim as my invention is:

1. In radiograph apparatus, a cassette, two fluorescent screens withinthe cassette between which a radiograph film may be placed, a blockimpervious to actinic rays formed in each screen, said blocks being inline with each other, and identifying indicia on the outside of thecassette formed of material opaque to X-rays, said indicia being locatedover the impervious blocks of the screens.

2. In radiograph apparatus, a cassette, two fluorescent screens withinthe cassette between which a radiograph film may be placed, a blockimpervious to actinic rays formed in each screen flush with the surfacethereof which comes into contact with the film, said blocks being inline with each other, and identifying indicia on the outside of thecassette formed of material opaque to X-rays, said indicia. beinglocated over the impervious blocks of the screens.

3. In radiograph apparatus, a cassette, two fluorescent screens withinthe cassette between which a radiograph film may be placed, a blockimpervious to actinic rays formed at a corner of each screen andextending into the screen some distance from each of the two sides atsaid corner, said blocks being in line with each other, and identifyinginidicia on the outside of the cassette formed of material opaque toX-rays, said indicia being located over the impervious blocks of thescreens.

4.111 radiograph apparatus, a cassette, two fluorescent screens withinthe cassette between which a radiograph film may be placed, each screenbeing formed with a defluorized area which is in line with thecorresponding area of the other screen, and identifying indicia on theoutside of the cassette formed of material opaque to X-rays, saidindicia being located over the defiuorized areas of the screens.

5. In radiograph apparatus, a cassette, two fluorescent screens withinthe cassette between which a radiograph film may be placed, a blockimpervious to actinic rays formed in each screen flush with the surfacethereof which comes into contact with the film, said blocks being inline with each other, a barrier in each screen surrounding its blockflush with the contact surface thereof, said barriers being formed ofma- :terial impervious toboth actinic rays and X-rays, and identifyingindicia on the outside of the cas- .sette formed of material opaque toX-rays, said indicia being located over the impervious blocks of thescreens.

.6. In radiograph apparatus, a fluorescent screen having .a blockimpervious to actinic rays formed therein flush with the surface thereofadapted to be brought into contact with a radioi aph film, and a barrierin the screen surrounding its block flush with the contact surfacethereof, said barrier being formed of material impervious to bothac-tiniic rays and X-rays.

GORDON L. LOTT.

References Cited in the file of this patent UNITED STATES PATENTS NumberI Name Date 1,396,415 Fried Nov. 8, 1921 2,077,500 Townsend et a1. Apr.20, 1,937 2,193,021 Dietz Mar. 12, 1940 2,344,824 Landis et a1 Mar. 21,1944 2,441,010 Dobbins May 4, 1948 2,585,551 Hofstadter Feb. '12, 1952

